JERUSALEM — Despite its confident saber-rattling, Israel’s concern is growing that the country is vulnerable to a devastating counterstrike if it attacks Iran’s nuclear program.

An announcement this week that a mobile rocket-defense system soon will be built just outside Tel Aviv - where Israel’s sprawling military headquarters sits smack in the middle of office towers, museums, night spots and hotels - caused some jitters.

Israeli officials cite intelligence reports that Tel Aviv would be a main target of any attack.

Increasingly, the debate in Israel is turning to whether a strike can do enough damage to the Iranian program to be worth the risks. Experts think that any attack would at best set back, but not cripple, the Iranians.

Israelis still remember Iraqi Scud missiles landing in the center of the country 20 years ago. In 2006, the Lebanese Hezbollah militia seemed able to rain rockets at will during a monthlong conflict with the Jewish state. A scathing government report issued months ago suggested the home front is still woefully unprepared.

In a questionably timed move, the Cabinet minister in charge of civil defense in recent days resigned to become the ambassador to faraway China.

Israeli Vice Prime Minister Dan Meridor, who also serves as minister of intelligence and atomic energy, indicated Saturday that Israel is facing a new type of peril.

“Whereas in the past, there was a battlefield where tanks fought tanks, planes fought planes, there was a certain push not to see the home front affected. Now the war is mainly in the home front,” said the usually tight-lipped Mr. Meridor.

“The whole of Israel [is vulnerable to] tens of thousands of missiles and rockets from neighboring countries. So of course we need to understand the change of paradigm,” he said. “If there is a war, and I hope there isn’t a war, they are not just going to hit Israeli soldiers. The main aim is at civilian populations.”

Thousands of rockets

Both Israel and the West think that Iran is trying to develop a nuclear bomb - a charge Tehran denies. Israel thinks a nuclear-armed Iran would be a threat to its very existence, citing Iranian leaders’ calls for its destruction.

Israel has welcomed international sanctions imposed on the Islamic regime, but it has pointedly refused to rule out military action. In recent weeks, top leaders have sent signals that patience is running thin.

An Israeli military strike would very likely draw an Iranian retaliation, experts think, which would involve either Iran firing its long-range Shahab missiles or acting via local proxies of Hezbollah in Lebanon, Hamas in Gaza or even Assad loyalists in Syria.

Experts think the experience of the 2006 war against Hezbollah, in which the guerrillas rained 4,000 rockets onto Israel, is just a small taste of what could lie ahead. The chief of military intelligence recently said that Israel’s enemies now have an estimated 200,000 rockets and missiles aimed at Israel.

But this time, Israel’s main population centers are thought to be possible targets.

In the past, rockets fired from Gaza or Lebanon have been directed at smaller, marginal communities, the largest being regional centers like Haifa in the north or Beersheba in the south.

Leaders think that Israel’s main cities would be targeted by more sophisticated, longer-range missiles.

Jerusalem is considered relatively safe because of its Islamic holy sites. But the Mediterranean coast, home to most of the country’s population, with Tel Aviv as the gleaming target at its center, seems like a very attractive target.

The business and cultural capital of the country, with a metropolitan population of more than 2 million, Tel Aviv is critical to Israel’s image of itself as a modern place with a Western lifestyle. Israel happily markets the city as a high-tech, fun-loving hub.

Untested city

Aside from a spate of then-Iraqi strongman Saddam Hussein’s rudimentary Scud missiles in 1991, the city has never truly been tested before.

Although the Scuds caused little damage, memories of that war are vivid. The strikes caused widespread panic and tens of thousands of people fled to safer areas of the country or left altogether.

A prolonged siege on the city today could likely fuel another exodus.

Israeli defense officials warn that Syria, a close Iranian ally, is thought to possess GPS-guided missiles and chemical weapons.

Hezbollah has greatly improved its arsenal since the war, and militants in the Gaza Strip, to Israel’s south, are thought to be smuggling powerful warheads from Libya.

The officials, speaking on the condition of anonymity because they were discussing a sensitive security matter, said intelligence reports indicate that Tel Aviv military headquarters will be targeted and an alternative site for military headquarters is being prepared.

Defense Minister Ehud Barak has estimated that an Iranian attack would claim fewer than 500 Israeli casualties - a statement intended to calm the nation, but which has achieved the opposite effect.

The concerns for the home front have dovetailed with fears around the world that an attack could unhinge the global economy and spur terrorist attacks against the West.

For the past five years, Matan Vilnai - a veteran Cabinet minister and one-time deputy military chief of staff - has been responsible for preparing such scenarios. Mr. Vilnai recently announced he was stepping down, leaving for China as Israel’s new envoy.

On Sunday, he gave the Cabinet a progress report on home-front preparations. His comments were not made available to the public, and Mr. Vilnai did not respond to requests for an interview by the Associated Press.

But Israeli media quoted the former general as being outraged at insinuations that he was “running away.”

Prime Minister Benjamin Netanyahu acknowledged after Mr. Vilnai’s presentation that more work must be done in “an era of threats to the Israeli home front.”